Defense Secretary Jim Mattis and a top aide to President Donald Trump have clashed over a number of Pentagon appointments, keeping some high-level positions empty for nearly two months, Defense News reported.

Mira Ricardel, who in her position at the Office of Presidential Personnel has been part of the nominee review, including conducting interviews, is viewed by Mattis supporters as a "roadblock" to the process, Defense News reported.

The Trump team sees her as someone who is looking out for the president, the outlet reported.

"She's extremely well respected and liked at the White House," one administration source told Defense News. "The White House thinks she's done great work in a difficult situation."

But after one "major clash," Mattis "told the White House either Mira goes, or he walks," an unnamed source told Defense News. "They blinked."

According to Defense News, Ricardel is now in line for a senior position with the Department of Commerce.

The administration source denied there was an "either-or" demand, saying clashes should be considered a "badge of honor" because Ricardel has held the line against "politically unacceptable" candidates.

"Mattis being upset with her has absolutely nothing to do with this," that source told the outlet. "She's doing that job until she can't anymore because of her nomination. . . . Jim Mattis has zero to do with her job prospects."

Defense News said the most recent name offered by Mattis as undersecretary of defense for policy – and rejected by the White House – was Anne Patterson, who signed a "Never Trump" letter last summer.

Two other nominees — Vincent Viola for secretary of the Army and Philip Bilden for secretary of the Navy — have withdrawn their nominations.

Defense Secretary Jim Mattis and a top aide to President Donald Trump have clashed over a number of Pentagon appointments, keeping some high-level positions empty for nearly two months, Defense News reported.